There are gas powered that aren't really heavy. I just made sure to have the straps adjusted correctly to take as much weight off of my arms/shoulders as possible.
When I used the heavier one, I made a harness that went over my shoulders and around my waist to help take even more of the weight off of my arms/shoulders. I added a piece to go across my back and chest, so that the straps stayed up on my shoulders :D:D:D